Hydroplane boat

ABSTRACT

A hydroplane boat of tunneled sponson form is rendered longitudinally stable by two pontoons having planing surfaces and mounted on boom structure in spaced relation astern of the main hull and laterally spaced to trail the respective sponsons. A cross boom between the pontoons is formed as an airfoil with adjustable angle of attack. The pontoons may be rotatable about vertical axes for steering, and the entire boom structure may be adjustable about a horizontal transverse axis to vary the effective angle of attack of the main hull.

United States Patent Granger 1 Mar. 14,1972

[54] HYDROPLANE BOAT [72] Inventor: Roger A. Granger, 20321 Shadon Mountain Rd., Walnut, Calif. 91789 [22] Filed: Sept. 14, 1970 [2i] Appl. No.: 72,078

[52] US. Cl. ..1 114/665 R [51] Int. Cl .363!) 1/20 [58] Field ofSearch ..114/66.5,66.5 S, 123

[56] References Cited UNITED STATES PATENTS 3,094,962 6/1963 Goar ..ll4/66.5R

3,522,785 8/1970 Thompson ..l 14/665 R Primary Examiner-Andrew H. Farrell Attorney-Charlton M. Lewis ABSTRACT A hydroplane boat of tunneled sponson form is rendered longitudinally stable by two pontoons having planing surfaces and mounted on boom structure in spaced relation astem of the main hull and laterally spaced to trail the respective sponsons. A cross boom between the pontoons is formed as an airfoil with adjustable angle of attack. The pontoons may he rotatable about vertical axes for steering, and the entire boom structure may be adjustable about a horizontal transverse axis to vary the effective angle of attack of the main hull.

9 Claims, 5 Drawing Figures Patented March 14, 1972 2 Sheets-Sheet 1 IwE/wae, 06 A. 694M659,

Patented March 14, 1972 2 Sheets-Sheet 2 HYDROPLANE BOAT This invention has to do with hydroplane boats, and relates particularly to hydroplanes designed primarily for speed.

An important object of the invention is to improve the inherent stability of hydroplane boats, thereby permitting safe operation at higher speeds and under a wider variety of water conditions than with conventional designs.

Conventional hydroplane boats normally have a forward structure on which the boat planes, typically comprising laterally spaced sponsons with a tunnel between them. The aft portion of the boat has a relatively flat bottom, which may provide a secondary planing surface during acceleration, but is raised nearly clear of the water when at speed by lift generated by the partially submerged propeller. A serious problem with such conventional hydroplanes is their tendency to lose longitudinal stability. In particular, a sudden deletion or drastic reduction of power allows the stem to drop. As a result, air may get under the bow and increase its aerodynamic lift sufficiently to flip the boat over. If longitudinal stability is sought by lengthening the hull, the weight and wetted area are both increased, requiring more horsepower which adds still more weight. The result is a definite limitation upon potential speed.

In accordance with the present invention, effectively positive longitudinal stability is obtained by providing two small auxiliary hulls or pontoons in spaced relation aft of the main hull. The pontoons are joined to the main hull by boom structure that is clear of the water. The two pontoons are laterally spaced from each other by a distance that corresponds generally to the spacing of the sponsons of the main hull. That spacing adds appreciably to the lateral stability of the boat, yet protects the pontoons from any rough water that might be encountered outboard of the main hull.

A particular advantage of the invention is that the engine and propeller can be placed relatively far forward. The engine weight is then supported primarily by the main sponsons. That fact, combined with the stabilizing action of the pontoons, greatly reduces the time required to reach planing speed. Also, the propeller lift, when at speed, is more nearly centered longitudinally, so that even abrupt cutting of the engine does not destroy longitudinal stability.

The auxiliary hulls or pontoons are preferably positioned far enough aft of the main hull to provide appreciable leverage in maintaining longitudinal stability of the boat. The greater that leverage the smaller are both the planing lift required of the pontoons when at speed and the buoyancy when at rest. By maintaining the hull at an effective planing angle as speed decreases, the invention inherently provides increased coasting ability.

In accordance with a further aspect of the invention, each of the pontoons is mounted on the boom structure for pivotal movement about a vertical axis, with cable controls for tuming them in unison for steering the boat. A small skeg on each pontoon makes such steering more positive and tends to stabilize the boat on the straightaway.

The boom structure typically includes a cross member between the pontoons. That member may be formed as an airfoil, producing enough lift at speed to reduce appreciably the drag of the pontoons, and further stabilizing the boat due to the inherent change of angle of attack of the airfoil with pitching of the boat. Such an airfoil may be made adjustable in pitch angle to modify the lift with varying weight of the pontoons, especially if fuel is carried in the pontoons. A fixed or adjustable airfoil may also be mounted on the main hull.

It is ordinarily preferred to mount the pontoons on boom structure that is fixedly carried'on the main hull. However, the invention includes the possibility of providing adjustment of part or all of the boom structure relative to the main hull, especially about a transverse horizontal pivot axis. Such adjustment permits variation of the relative angles of attack of the main hull and the pontoons. If the pivot axis is close to, or within, the main hull, such adjustment has the primary result of altering directly the angle of attack of the main hull.

A full understanding of the invention, and of its further objects and advantages, will be had from the following description of a preferred manner of carrying it out. The particulars of that description, and of the accompanying drawings which form a part of it, are intended only as illustration and not as a limitation upon the scope of the invention, which is defined in the appended claims.

In the drawings:

FIG. 1 is a schematic perspective representing an illustrative hydroplane boat embodying the invention;

FIG. 2 is a front elevation, partly broken away and at larger scale than FIGS. 3 and 4;

FIG. 3 is a plan;

FIG. 4 is a side elevation; and

FIG. 5 is a fragmentary schematic section at enlarged scale on line 5-5 of FIG. 3.

A hydroplane boat embodying the invention typically comprises the main hull 10, the two auxiliary hulls or pontoons 32 and 34, and the boom structure 40 by which the pontoons are joined to the main hull.

The main hull is of tunneled sponson form, with the right and left sponsons 12 and 14 and the tunnel formation 16 between them. That tunnel formation is shown as a single tunnel, but may comprise multiple tunnels as in conventional hydroplane construction. The sponsons typically terminate aft in a double step, as shown at 18 in FIG. 4, and their primary planing surfaces 19 and general configuration may be generally conventional. Small stabilizing skegs are indicated at 21. The stem 20 of main hull 10 is typically of transom form, but is spaced a relatively short distance astern of step structure 18, as compared to conventional hydroplane design. In fact, the main hull of the present boat is typically so short that, by itself, it would afford completely inadequate longitudinal stability. The cockpit 22, driver's seat 24 and steering wheel 26 may be substantially conventional.

Pontoons 32 and 34 are formed with modified V-bottoms, the inner flanks 35 of those bottoms being virtually horizontal and acting as primary planing surfaces, and the outer flanks 36 being relatively steeply angled to provide stability against slewing. The pontoon stems 37 are typically flat, as shown, but may be of fuller form, as to provide increased buoyancy when at rest. The small skegs 38 are illustrative of the wide variety of detailed fin forms that may provide directive reaction against the water.

Boom structure 40 typically comprises the right and left booms 42 and 44 and the transverse strut 50 which interconnects the booms at their aft ends. The booms as shown are rigidly mounted at their forward ends on main hull 10 with appropriate fairing to reduce air resistance. Each boom is typically of triangular section and may be formed of aluminum sheet material with internal reinforcing tubes 48 at the corner edges, as shown in FIG. 2.

Each pontoon carries a rigidly mounted vertical post struc ture 54 which projects upwardly into the aft end section of its supporting boom (FIG. 5) and is joumaled by the upper and lower bearings 56 and 57 with respect to the boom for pivotal movement about a vertical axis 55. That movement is controlled by the steering cables 58, which are coupled to post 54 by a section of sprocket chain and a sprocket wheel 59 that is rigidly mounted on the post. Cables 58 are led forward within the boom, typically guided within the two upper reinforcing tubes 48, and are coupled to steering wheel 26 in such a way that both pontoons are driven in unison.

Transverse strut 50 is preferably formed as an airfoil and mounted on the booms 42 and 44 by means of the brackets 52 which permit limited pivotal movement about a common horizontal axis 51 which is longitudinal of the strut. That pivotal movement is controlled in any suitable manner, as by the control cables 53 which are connected to upper and lower brackets on the strut and are led forward to a control mechanism in the cockpit, not explicitly shown.

The boat is driven by an engine which is typically of outi board type and mounted on the transom stern of the main hull;

as indicated at 60. The propeller is located at such height with relation to the planing surfaces of the main hull and of the pontoons that when the boat is at speed the water surface just clears the propeller hub. Dual outboard engines may also be used if desired. lf another type of power plant is preferred, a suitable supporting frame can readily be provided for mounting it at 61 in the same general position as shown for outboard engine 60.

A typical waterline when the boat is at rest is indicated schematically at 64 in FIG. 4. The propeller is then fully immersed. As power is applied, the propeller exerts a strong clockwise torque on the boat, as seen in FIG. 4, tending to lift the main hull and to further submerge the pontoons, shifting the waterline to such a position as 66. As speed is acquired, planing action becomes dominant, and the main hull and the pontoons then tend to climb together from the water, maintaining a relatively uniform pitch angle with firmly controlled longitudinal stability at all times. A typical waterline for a speed of 50 m.p.h. is indicated at 68. At full planing speed and with full power, the waterline is typically as shown at 70, with the main hull and pontoons barely skimming the surface, and with only the lower blades of the propeller immersed and the propeller hub clear of the water. The vertical lift generated by the propeller acts primarily to raise the main hull, typically leaving only enough weight supported by planing surfaces 19 to insure stability and control. Pontoons 32 and 34 also carry only enough weight to maintain them firmly at the water surface. If fuel is carried in tanks in the pontoons, the aerodynamic lift of strut 50 is preferably adjusted to maintain substantially uniform effective load on the planing surfaces of the pontoons as the fuel is consumed. That lift may be made either positive or negative as required under various conditions of wind, sea and the like.

In accordance with a further aspect of the invention, an aerodynamic lifting vane may be mounted on main hull 10, as indicated schematically at 80. Rigid vertical posts 82 carry pivot bearings by which the vane is supported on a horizontal pivot axis 81. The rotational position of the vane about that axis is adjustably defined by the hydraulic cylinders 84, which are driven in parallel by hydraulic control mechanism of conventional type. The effective lift exerted by vane 80 can be varied over a wide range, both positive and negative, and is typically adjusted to take all weight off the planing surfaces of the main hull except that required to provide the desired stability and control. Vane 80 is preferably arranged so that it can be easily dismounted when not required.

I claim:

1. A hydroplane boat comprising the combination of a main hull having a longitudinal axis and a tunneled undersurface adapted to plane on the water surface in response to forward boat movement,

two buoyant hull units having respective undersurfaces adapted to plane on the water surface in response to forward movement,

structure connecting the hull units to the main hull with the hull units spaced aft of the main hull and spaced laterally with respect to each other on opposite sides of the longitudinal axis, said connecting structure being spaced above the water surface under all normal operating conditions of the boat,

power means for driving the boat forward at a speed to cause planing of the main hull and of the hull units,

3. A hydroplane boat as defined in claim 2, and wherein said transverse member has the cross-sectional form of an I airfoil and exerts aerodynamic lift at normal operating speed of the boat.

4. A hydroplane boat as defined in claim 3, and wherein said transverse member is mounted for rotational movement about its longitudinal axis,

said boat including means for controllably varying the rotational position of the transverse member to vary the aerodynamic lift thereof.

5. A hydroplane boat as defined in claim 1, and wherein said connecting structure comprises an elongated boom of hollow triangular cross-section interconnecting the main hull and each hull unit.

6. A hydroplane boat as defined in claim 1, and wherein said main hull has a transom stern,

and said power means comprise an outboard engine mounted at the stern of the main hull with its propeller adjacent the center of gravity of the entire boat so that upward water thrust on the propeller due to propeller rotation tends to lift the main hull clear of the water during full speed operation of the boat.

7. A hydroplane boat as defined in claim 1, and wherein the hull units are mounted for rotational movement about respective generally vertical rotation axes,

said steering means comprising water engaging vane struc tures mounted on the respective hull units and means for controllably driving the rotation of the hull units with respect to said connecting structure.

8. A hydroplane boat comprising in combination a main hull having a tunneled undersurface adapted to plane on the water surface in response to forward movement and having a transom stern,

power means for driving the boat at planing speed and including a propeller mounted aft of the stern on a propeller axis adjacent the plane of said undersurface,

structure mounted on the main hull and extending aft of the stern thereof in spaced relation above the water surface,

said structure carrying buoyant means spaced aft of the stern for supporting said structure and for stabilizing the boat with respect to pitch when the boat is at rest, and carrying laterally spaced planing surfaces for supporting said structure and for stabilizing the boat with respect to pitch when the boat is at planing speed.

9. A hydroplane boat as defined in claim 8, and in which the center of gravity of the entire boat is adjacent the propeller,

upward water thrust on the propeller due to propeller rotation tending to lift the main hull clear of the water during full speed operation of the boat. 

1. A hydroplane boat comprising the combination of a main hull having a longitudinal axis and a tunneled undersurface adapted to plane on the water surface in response to forward boat movement, two buoyant hull units having respective undersurfaces adapted to plane on the water surface in response to forward movement, structure connecting the hull units to the main hull with the hull units spaced aft of the main hull and spaced laterally with respect to each other on opposite sides of the longitudinal axis, said connecting structure being spaced above the water surface under all normal operating conditions of the boat, power means for driving the boat forward at a speed to cause planing of the main hull and of the hull units, and means for steering the boat, said hull units increasing the stability of the boat with respect to roll by virtue of their said lateral spacing, and producing stability of the boat with respect to pitch by virtue of their said spacing aft of the main hull.
 2. A hydroplane boat as defined in claim 1, and wherein said connecting structure comprises two elongated structural members extending between the main hull and the respective hull units, and an elongated transverse member essentially interconnecting the hull units independently of the main hull.
 3. A hydroplane boat as defined in claim 2, and wherein said transverse member has the cross-sectional form of an airfoil and exerts aerodynamic lift at normal operating speed of the boat.
 4. A hydroplane boat as defined in claim 3, and wherein said transverse member is mounted for rotational movement about its longitudinal axis, said boat including means for controllably varying the rotational position of the transverse member to vary the aerodynamic lift thereof.
 5. A hydroplane boat as defined in claim 1, and wherein said connecting structure comprises an elongated boom of hollow triangular cross-section interconnecting the main hull and each hull unit.
 6. A hydroplane boat as defined in claim 1, and wherein said main hull has a transom stern, and said power means comprise an outboard engine mounted at the stern of the main hull with its propeller adjacent the center of gravity of the entire boat so that upward water thrust on the propeller due to propeller rotation tends to lift the main hull clear of the water during full speed operation of the boat.
 7. A hydroplane boat as defined in claim 1, and wherein the hull units are mounted for rotational movement about respective generally vertical rotation axes, said steering means comprising water engaging vane structures mounted on the respective hull units and means for controllably driving the rotation of the hull units with respect to said connecting structure.
 8. A hydroplane boat comprising in combination a main hull having a tunneled undersurface adapted to plane on the water surface in response to forward movement and having a transom stern, power means for driving the boat at planing speed and including a propeller mounted aft of the stern on a propeller axis adjacent the plane of said undersurface, structure mounted on the main hull and extending aft of the stern thereof in spaced relation above the water surface, said structure carrying buoyant means spaced aft of the stern for supporting said structure and for stabilizing the boat with respect to pitch when the boat is at rest, and carrying laterally spaced planing surfaces for supporting said structure and for stabilizing the boat with respect to pitch when the boat is at planing speed.
 9. A hydroplane boat as defined in claim 8, and in which the center of gravity of the entire boat is adjacent the propeller, upward water thrust on the propeller due to propeller rotation tending to lift the main hull clear of the water during full speed operation of the boat. 